The present invention relates to a process for the preparation of coke from coal in a coke oven, to a coke oven and to the use of this coke oven to prepare coke from coal.

Background Art

US 8,980,063 B2 relates to an air proportioning system for secondary air in coke ovens. According to this document, the temperature of the top chamber and the temperature of the sole chamber are measured. The amount of air that is introduced into the sole chamber is then calculated based on the concentration of oxygen in the sole chamber and on the ratio between the temperature of the top chamber and the temperature of the sole chamber.

US 2009/0032382 Al discloses a coking oven comprising a measuring device for measuring the concentration of gaseous constituents of the coke and a measuring device for measuring the temperature in the coke oven sole, wherein, based on these values, a process control computer determines the amount of air that shall be supplied into the primary chamber and into the secondary chamber during the coking process.

The person having ordinary skill in the art in the technical field of processes and methods for producing coke from naturally occurring coal knows that such a process is preferably conducted in a heat-recovery coke making plant, wherein the complete gas produced from coal carbonization is combusted directly inside the coke oven. Therewith, a mixture of unburned gas produced from coal and off-gas of the combustion is obtained. This mixture is then led through vertical ducts in the sidewalls (downcomers) into the heating flow system of the open sole. Here the combustion is completed with a staged supply of air so that the coal layer is evenly heated from the top and the bottom.

Processes that are known from the prior art often have the problem that the amount of air which is introduced into the primary chamber and into the secondary chamber is determined by a known theoretical gas release. However this theoretical gas release does not consider the variation in process and raw materials, for example chemical composition and/or moisture, of the coal. Further, the methods for determining the amount of air that has to be introduced into the primary or secondary chamber of a coke oven that make use of values of concentration of oxygen and/or burnable gas in the gas streams can still be improved. It is therefore an object of the present invention to provide a process for producing coke from coal which does not comprise the above-mentioned disadvantages. In particular, a corresponding process shall be provided in which all gas released from coal cake is burned inside the oven to obtain increased process efficiency. Further, preferably no gas shall be burned inside the collector to preserve the asset. In addition, the net cooking time shall be reduced to gain the productivity. At the same time, the burn loss shall be reduced to decrease losses and to further gain the productivity

Summary of Invention

The above mentioned objects are solved by the process for the preparation of coke from coal in a coke oven (1) comprising at least one primary chamber (10), at least one secondary chamber (20) located beneath the primary chamber (10), at least one connection (30) between the at least one primary chamber (10) and the at least one secondary chamber (20), at least one collector (40) which is connected to the at least one secondary chamber, at least one moiety for providing air (50) to the at least one primary chamber and at least one moiety for providing air (60) to the at least one secondary chamber, comprising at least the following steps:

(A) Providing coal in the at least one primary chamber (10) of the coke oven (1),

(B) At least partial combustion of gas released from the coal in the at least one primary chamber by introducing air through the at least one moiety for providing air (50) to the at least one primary chamber, and carbonization of the coal to obtain coke at a temperature Tl,

(C) Combustion of the remaining gas released from the coal in the secondary chamber (20) at a temperature T2, wherein this remaining gas has been guided to the at least one secondary chamber (20) through the connection (30) between the at least one primary chamber (10) and the at least one secondary chamber (20), by introducing air through the at least one moiety for providing air (60) to the at least one secondary chamber and

(D) Removing the off-gas obtained from steps (B) and (C) through the at least one collector (40), wherein temperature T2 is measured in predefined time intervals during steps (B), (C) and (D) and the at least one moiety for providing air (60) to the at least one secondary chamber is adjusted depending on a comparison of T2 with a value SP2 calculated from T2 of the foregoing time interval, wherein the first value SP2 is predefined at the beginning of step (B), by a coke oven (1), comprising at least one primary chamber (10), at least one secondary chamber (20) located beneath the primary chamber, at least one connection (30) between the at least one primary chamber (10) and the at least one secondary chamber (20), at least one collector (40) which is connected to the at least one secondary chamber (20), at least one moiety for providing air (50) to the at least one primary chamber, at least one moiety for providing air (60) to the at least one secondary chamber and a central processing unit (70), wherein at least one thermocouple (80) is present and the at least one primary chamber (10) and at least one thermocouple (90) is present at the at least one secondary chamber (20), wherein the central processing unit (70) is enabled to compare a value SP2 and a temperature T2 that is measured in predefined time intervals and to adjust the at least one moiety for providing air (50) to the at least one primary chamber and the at least one moiety for providing air (60) to the at least one secondary chamber, and by the use of a coke oven according to the present invention to prepare coke from coal. Detailed Description of the Invention

The present invention relates to a process for the preparation of coke from coal by carbonization. This method to prepare coke is generally known to the skilled artisan. In general, a type of coke oven is used, wherein naturally occurring coal is provided in a so called primary chamber or "Top". This primary chamber comprises openings through which preferably air from the outside is sucked in in order to burn the gas that is let out of the coal. The primary chamber is connected by so called downcomers to a secondary chamber that is located beneath the primary chamber. This secondary chamber also comprises openings through which preferably air is sucked in from the outside so that preferably complete combustion of the gas coming from the first chamber through the downcomers is made possible.

The process according to the present invention is conducted in a coke oven corresponding to the ones that are already known to the skilled artisan. The specific feature of the process according to the present invention is that at least the temperature T2 in the secondary chamber is measured in predefined time intervals and the acquired values are compared to so-called setting points SP2s in order to obtain the information how temperature T2 develops during the process and if the moieties for introducing air into the secondary chamber shall be opened or closed.

The coke oven which is used in the process according to the present invention comprises at least one primary chamber (10), which is also called "Top", at least one secondary chamber (20), which is also called "Sole" or "Sole flue", located beneath the primary chamber (10), at least one connection (30) between the at least one primary chamber (10) and the at least one secondary chamber (20), which is also called downcomer, at least one collector (40) which is connected to the at least one secondary chamber, at least one moiety for providing air (50) to the at least one primary chamber and at least one moiety for providing air (60) to the at least one secondary chamber. A coke oven which is preferably used in the process according to the present invention is shown in figure I .

The present invention therefore also relates to a coke oven (1), comprising at least one primary chamber (10), at least one secondary chamber (20) located beneath the primary chamber, at least one connection (30) between the at least one primary chamber (10) and the at least one secondary chamber (20), at least one collector (40) which is connected to the at least one secondary chamber (20), at least one moiety for providing air (50) to the at least one primary chamber, at least one moiety for providing air (60) to the at least one secondary chamber and a central processing unit (70), wherein at least one thermocouple (80) is present at the at least one primary chamber (10) and at least one thermocouple (90) is present at the at least one secondary chamber (20), wherein the central processing unit (70) is enabled to compare a value SP2 and a temperature T2 that is measured in predefined time intervals and to adjust the at least one moiety for providing air (50) to the at least one primary chamber and the at least one moiety for providing air (60) to the at least one secondary chamber.

The central processing unit according to the present invention can be any means which is known to the skilled artisan to be able to collect, handle and calculate data, for example temperatures, grades of opening of valves, time intervals etc. Preferably, the central processing unit may be a PLC (Program Logic Control) equipped with a suitable software. Preferably, the coke oven which is used in the process according to the present invention comprises one primary chamber (10), one secondary chamber (20), located beneath the primary chamber (10), a number of, for example 2 to 6, connections (30) between the primary chamber (10) and the secondary chamber (20), 1 to 3 collector(s) (40) which is/are connected to the secondary chamber, a number of, for example 2 to 20, moieties for providing air (50) to the primary chamber and a number of, for example 2 to 20, moieties for providing air (60) to the secondary chamber.

According to the present invention the at least one moiety for providing air (50) to the at least one primary chamber may be any moiety which is suitable for providing air to the at least one primary chamber, for example selected from the group consisting of valves, dampers, gates and combinations thereof. The at least one moiety for providing air (60) to the at least one secondary chamber may be any moiety which is suitable for providing air to the at least one secondary chamber, for example selected from the group consisting of valves, dampers and combinations thereof.

The moieties for introducing air into the primary chamber or into the secondary chamber may be symmetrical or asymmetrical. Preferably, the moieties are symmetrical. According to this preferred embodiment, the gas air mixture is particularly homogeneously mixed.

According to a particularly preferred embodiment of the present invention, the moieties for introducing air into the secondary chamber are symmetrical. According to this preferred embodiment, the gas air mixture is particularly homogeneously mixed.

The single steps of the process according to the present invention are explained in detail in the following.

According to the present invention, the process steps (A), (B), (C) and (D) are generally conducted sequentially. However it is also possible and preferred that at least some of steps (A), (B), (C) and (D) are at least partially conducted at the same time. For example step (A) is conducted, followed by (B), (C) and (D), wherein steps (B), (C) and (D) are conducted at least partially at the same time. Step (A):

Step (A) of the process according to the present invention comprises providing coal in the at least one primary chamber (10) of the coke oven (1).

According to the present invention any kind of coal that is suitable to prepare coke therefrom can be used. The person having ordinary skill in the art does know how the quality features of coal which can be introduced into the process according to the present invention shall be.

The amount of coal which is provided in step (A) of the process according to the present invention depends on the size of the coke oven that is used for the process according to the present invention, for example, a primary chamber of a suitable coke oven has a length of 10 to 15 m, a width of 3 to 4 m and a height of 1 to 3 m. Therefore, for example 33 to 65 tons of coal can be provided in step (A) of the process according to the present invention. The coal can be introduced into the primary chamber of the coke oven by any means that are generally known to the skilled artisan, for example by a horizontal charging machine positioned in front of the oven.

Step (B):

Step (B) of the process according to the present invention comprises the at least partial combustion of gas released from the coal in the at least one primary chamber by introducing air through the at least one moiety for providing air (50) to the at least one primary chamber, and carbonization of the coal to obtain coke at a temperature Tl .

Burnable gases like hydrogen, hydrocarbons, for example CH ₄ , C2H ₄ , xylene, benzene, toluene, sulfur and nitrogen are evolved from the coal which is provided in the primary chamber of the coke oven. According to step (B) of the process according to the present invention air is introduced through the at least one moiety for providing air (50) to the at least one primary chamber. A chemical reaction between the burnable gas and oxygen which is present in the air takes place so that the burnable gas is combusted in step (B) of the process according to the present invention. According to the present invention, the air which is used in steps (B) and/or (C) of the process according to the present invention is preferably usual air which is present in the atmosphere. The composition of air being about 78% nitrogen, 21% oxygen, 0,9% Argon, remainder being carbon dioxide and other gases in minor amounts, is generally known to the skilled artisan. The amount of burnable gas that is evolved by the coal in step (B) of the process according to the present invention depends on the type and amount of coal which is present in the coke oven. In addition, the amount of burnable gas that is evolved by the coal depends on the temperature which is present in the primary chamber.

According to a preferred embodiment of the process according to the present invention, the primary chamber and the coal which is inside this primary chamber is not heated externally to start the combustion, but combustion of burnable gas evolved from the coal and oxygen introduced by air starts by itself, preferably as soon as burnable gas and air are in contact. During the process, in particular when burnable gas is combusted in the at least one secondary chamber according to step (C) of the process according to the present invention, the heat obtained from this combustion is used to heat the coal present in the at least one primary chamber from the bottom. Therewith, according to a preferred embodiment of the present invention, evolvement of burnable gas from the coal present in the at least one primary chamber can be enhanced.

According to the present invention, the number of moieties for introducing air into the primary chamber (50) can be adjusted in a way that a suitable amount of air is let in. For example, 2 to 20, preferably 4 to 16, moieties for introducing air into the primary chamber (50) can be present. According to the present invention, the at least one moiety for introducing air into the primary chamber (50) is designed that the grade of opening can be adjusted from completely closed, i.e. 0%, to completely open, i.e. 100%. In case that more than one moiety for introducing air (50) into the primary chamber is present the grade of opening can the same for all moieties (50) present or the grades of opening can be different for all moieties (50) present.

The size of the moieties for introducing air into the primary chamber (50) can be selected in a way that a suitable amount of air can be introduced into the primary chamber. For example each moiety may have a diameter of 70 to 300 mm, preferably 120 to 240 mm, particularly preferably 140 to 200 mm. Therefore, a suitable area of the openings may be 3848 to 70650 mm ² , preferably 11304 to 45216 mm ² , particularly preferably 14896 to 31400 mm ² .

As soon as the combustion has started, temperature Tl will rise. Temperature Tl that is present in step (B) of the process according to the present invention may be 800 to 1100 °C, preferably 900 to 1100 °C, more preferably 1000 to 1100 °C. The present invention therefore preferably relates to the process according to the present invention, wherein Tl is 800 to 1100 °C preferably 900 to 1100 °C, more preferably 1000 to 1100 °C.

As already outlined above, a key feature of the process according to the present invention is that temperature T2 is measured in predefined time intervals during steps (B), (C) and (D), and the at least one moiety for providing air (60) to the at least one secondary chamber is adjusted depending on a comparison of T2 with a value SP2 calculated from T2 of the forgoing time interval, wherein the first value SP2 is predefined at the beginning of step (B).

According to a further preferred embodiment, the present invention relates to the process according to the present invention, wherein temperature Tl is also measured in predefined time intervals during steps (B), (C) and (D), and the at least one moiety for providing air (50) to the at least one primary chamber is adjusted depending on a comparison of Tl with a predefined value SPl.

According to the present invention the comparison of Tl and SPl provides information how much the moieties for introducing air (50) into the primary chamber shall be opened or closed in order to have the exact amount of air in the primary chamber.

The present invention therefore particularly preferably relates to the process according to the present invention, wherein temperature T2 is measured in predefined time intervals during steps (B), (C) and (D), and the at least one moiety for providing air (60) to the at least one secondary chamber is adjusted depending on a comparison of T2 with a value SP2 calculated from T2 of the foregoing time interval, wherein the first value SP2 is predefined at the beginning of step (B) and temperature Tl is also measured in predefined time intervals during steps (B), (C) and (D), and the at least one moiety for providing air (50) to the at least one primary chamber is adjusted depending on a comparison of Tl with a predefined SPl.

According to a preferred embodiment of the present invention, at least one thermocouple is present in the at least one primary chamber to acquire temperature Tl. The location where the thermocouple is located in the primary chamber can generally be selected by a person having ordinary skill. Preferably, temperature Tl is acquired by a thermocouple that is located at the middle of the length of the oven and may be 300 to 500 mm from the oven top in the at least one primary chamber. According to the present invention, in general any thermocouple which is known to the skilled artisan can be used to acquire temperature Tl . Preferably a thermocouple is used comprising a positive thermoelement comprising platinum and rhodium, for example 10% by weight rhodium, and a negative thermoelement comprising platinum. Such a thermocouple is able to acquire temperatures in a range of 0 to 1480 °C, wherein temperatures of up to 1760 °C are also possible for short time periods.

According to a further preferred embodiment, the present invention relates to the process according to the present invention, wherein Tl and T2 are measured by thermocouples present in the at least one primary chamber (10) or in the at least one secondary chamber (20), respectively.

According to a preferred embodiment of the present invention air is introduced into the primary chamber in step (B) of the process according to the present invention by sucking it through the at least one moiety for introducing air into the primary chamber (50). According to a preferred embodiment, the amount of air that is introduced into the primary chamber is 1000 to 1500 kg/hr, preferably 1100 to 1450 kg/hr, more preferably 1150 to 1400 kg/hr.

According to the present invention, a temperature Tl is measured and this temperature Tl is compared to a predefined setting point SP1. The setting point SP1 in step (B) is preferably predefined by the operator of the process and may be 1200 to 1380 °C, preferably 1300 to 1350 °C. The comparison of Tl and the first SP1 is made to obtain a value of how the at least one moiety for introducing air (50) into the at least one primary chamber shall be opened or closed. After a certain time interval, temperature Tl is measured again and is then compared to SP1 again. In each time interval, the comparison between Tl and SP1 provides information about the development of Tl and if and how much the moiety for introducing air into the primary chamber shall be opened or closed. Therewith, which each comparison in each time interval the at least one moiety to introduce air (50) into the at least one primary chamber is adjusted to have the exact amount of air in the primary chamber.

Generally, the time intervals can be selected by a person having ordinary skill in the art to obtain a suitable process. According to preferred embodiment, the time interval in the process according to the present invention is 5 to 30 min, preferably 10 to 25 min, more preferably 15 to 22 min. Further preferred, the time interval is kept constant during the whole process. Depending on the result of the comparison of Tl and SP1, a central processing unit gives a signal to the at least one moiety for introducing air (50) into the at least one primary chamber to open or close this moiety. For example, according to a preferred embodiment of the present invention the at least one moiety for introducing air (50) to the at least one primary chamber is closed completely, if Tl is higher SP1 + 100.

Further, if a temperature Tl in the primary chamber has been acquired that is higher than a certain temperature which depends on the coke oven and which is predefined in order to avoid damages to the oven, in particular to the bricks, the central processing unit preferably gives a signal to the at least one moiety for introducing air (50) into the at least one primary chamber to close moiety completely. For example, the temperature Tl at which the central processing unit closes moiety (50) completely is higher than 1350 °C, preferably higher than 1360 °C, particularly preferably higher than 1370 °C, for example 1380 °C.

Further, if a temperature Tl in the primary chamber has been acquired that is lower than the above mentioned temperature which depends on the coke oven and which is predefined in order to avoid damages to the oven, in particular to the bricks, the central processing unit will start the sequence of acquiring temperatures Tl in certain time intervals and comparing them with SP1.

According to a further preferred embodiment, the central processing unit will check the cooking time of the process according to the present invention. According to the present invention, the cooking time is the actual time which the actual coal mass is in the oven. The cooking time starts when a new coal mass is charged in the oven, the Central Unit can get it by temperature Tl or external signal, when a new coal mass is charged. Preferably, in case that a certain value of the cooking time is measured, for example less than 50 hours, preferably less than 40 hours, more preferably less than 30 hours, the central processing unit will send a signal to the to the at least one moiety for introducing air (50) into the at least one primary chamber to open it completely, i.e. to 100%.

During step (B) temperature Tl is acquired and compared to SP1 after each time interval. During the process, if the cooking time increases and gets higher than the above mentioned value, for example higher than 30 hours, preferably higher than 40 hours, more preferably higher than 50 hours, the degree of opening of to the at least one moiety for introducing air (50) into the at least one primary chamber depends on a mathematical formula. According to a preferred embodiment of the present invention, the at least one moiety for introducing air (50) into the at least one primary chamber is opened completely, i.e. to 100%, if the top temperature Tl in [°C] is lower than SP1 - 100 in [°C].

According to a further preferred embodiment, if temperature Tl in [°C] is higher than SP1 - 100 in [°C], the grade of opening of the at least one moiety for introducing air (50) into the at least one primary chamber is determined by mathematical formula (1):

Position of top valve in (%) = SP1 in (°C) - Tl in (°C) (1).

According to this preferred embodiment of the process according to the present invention, the opening of at least one moiety for introducing air (50) into the at least one primary chamber will range from 100%, i.e. completely open, to 0%, i.e. completely closed.

The combustion that takes place in step (B) of the process according to the present invention gives rise to a gas mixture comprising burnable gas that has not yet been burned in step (B), off-gas that has been obtained from the chemical reaction between the burnable gas and oxygen during combustion and air. For example, the mixture which is obtained in step (B) of the process according to the present invention may comprise 40 to 80 Vol-%, preferably 50 to 70 Vol.-%, burnable gas selected from the group consisting of hydrogen, carbon and sulfur and mixtures thereof, 20 to 60 Vol.-%, preferably 30 to 50 Vol.-% off-gas and 40 to 80 Vol.- %, preferably 50 to 70 Vol.-%, air.

According to a preferred embodiment of the process according to the present invention, 40 to 80% by weight of gas released from the coal are burned in the at least one primary chamber (10) of the coke oven (1), and 20 to 60% by weight of gas released from the coal are burned in the at least one secondary chamber (20) of the a coke oven (1), wherein the amounts of burned gas in the at least one primary chamber and in the at least one secondary chamber preferably add up to 100% by weight. In case that the amounts of burned gas in the at least one primary chamber and in the at least one secondary chamber do not add up to 100% by weight, but add up to an amount below 100% by weight, a certain amount of gas is burned in the collector (40). However, preferably, combustion of burnable gas in the collector (40) shall be avoided according to the present invention. According to a preferred embodiment of the present invention, air is introduced into the primary chamber in step (B) of the process according to the present invention by sucking it from the environment into the primary chamber through the at least one moiety (50). More preferably air is introduced into the primary chamber with an average flow of 1000 to 1500 kg/hr, preferably 1100 to 1450 kg/hr, for example 1350 kg/hr, which is the sum of air which is introduced through all moieties (50) present in each case.

Air which is introduced into the primary chamber is then mixed with the gas released from the coal cake. The average of gas flow of burnable gas released from the coal cake is 100 to 350 kg/hr, preferably 150 to 325 kg/hr, more preferably 200 to 300 kg/hr, for example 254 kg/hr. The burnable gas released from the coal is preferably partially burned in the primary chamber and the remaining burnable gas is guided to the secondary chamber.

According to a preferred embodiment, the mixture of gas that is obtained after combustion in step (B) of the process according to the present invention is directly guided into the secondary chamber of the coke oven through the connection (30) between the at least one primary chamber (10) and the at least one secondary chamber (20).

Generally, the gas that is obtained in step (B) flows from the primary chamber to the secondary chamber by itself, i.e. that no moieties for moving the gas stream, like pumps, are necessary in the coke oven and process according to the present invention.

Step (C):

Step (C) of the process according to the present invention comprises the combustion of the remaining gas released from the coal in the secondary chamber (20) at a temperature T2, wherein this remaining gas has been guided to the at least one secondary chamber (20) through the connection (30) between the at least one primary chamber (10) and the at least one secondary chamber (20), by introducing air through the at least one moiety for providing air (60) to the at least one secondary chamber.

According to the present invention, a mixture of gas obtained from step (B) comprising combustible gas that has not been burned yet, off-gas and air is guided to the at least one secondary chamber (20) through the connection (30) between the at least one primary chamber (10) and the at least one secondary chamber (20). The remaining burnable gas is then combusted in the secondary chamber by introducing air through the at least one moiety for providing air (60) to the at least one secondary chamber.

According to the present invention, the number of moieties for introducing air (60) into the secondary chamber can be adjusted in a way that a suitable amount of air is let in. For example 2 to 20, preferably 4 to 16, moieties for introducing air into the secondary chamber can be present to introduce air into the secondary chamber. According to the present invention, the at least one moiety for introducing air into the secondary chamber (60) is designed that the grade of opening can be adjusted from completely closed, i.e. 0%, to completely open, i.e. 100%. In case that more than one moiety for introducing air (60) into the secondary chamber is present the grade of opening can the same for all moieties (60) present or the grades of opening can be different for all moieties (60) present.

The size of the moieties for introducing air into the secondary chamber can be selected in a way that a suitable amount of air can be introduced into the secondary chamber. For example each moiety may have a measure of 100 mm to 250 mm height and 100 mm to 250 mm length, preferably 120 mm to 200 mm height and 120 mm to 200 mm length, particularly preferably 130 mm to 180 mm height and 130 mm to 180 mm length. Therefore, a suitable area of the openings may be 10000 to 62500 mm ² , preferably 14400 to 40000 mm ² , particularly preferably 16900 to 32400 mm ² .

According to a preferred embodiment of the present invention, the complete amount (100% by weight) of the gas released from coal is combusted in steps (B) and (C). Therefore, a particular advantage of the process according to the present invention is that no gas is combusted in the collector.

According to a preferred embodiment of the present invention, the secondary chamber in which step (C) is conducted is divided into certain segments, for example 1 to 6 segments. The combustion which takes place in step (C) may occur in any of the segments or, as an alternative, may occur in only some of these segments. Most preferably, the secondary chamber is divided in 6 segments, wherein the combustion occurs in segments 1 and 4, followed by segments 2 and 5, followed, if necessary, by segments 3 and 6. According to a preferred embodiment of the present invention, the at least one moiety for introducing air (60) into the secondary chamber is symmetrical. According to this preferred embodiment, the gas air mixture is homogeneously mixed.

According to a preferred embodiment of the present invention, at least one thermocouple is present in the at least one secondary chamber to acquire temperature T2. The location where the thermocouple is located in the secondary chamber can generally be selected by a person having ordinary skill in the art. Preferably, the thermocouple is located at a location of the secondary chamber where most of the gas is burned to have it present at the location of highest temperature in the secondary chamber.

According to the present invention, in general any thermocouple which is known to the skilled artisan can be used to acquire temperature T2. Preferably, a thermocouple is used as already defined in respect of step (B) above.

Temperature T2 in step (C) of the process according to the present invention is in general 900 to 1390 °C, preferably 1050 to 1370 °C, more preferably 1100 to 1350 °C. Temperature T2 which is present in the secondary chamber may preferably not exceed 1500 °C.

The present invention therefore preferably relates to the process according to the present invention, wherein T2 is 900 to 1390 °C, preferably 1050 to 1370 °C, more preferably 1100 to 1350 °C.

According to a preferred embodiment of the present invention air is introduced into the secondary chamber in step (C) of the process according to the present invention by sucking it through the at least one moiety for introducing air into the secondary chamber (60). According to a preferred embodiment, the amount of air that is introduced into the secondary chamber is 1500 to 2500 kg/hr, preferably 1700 to 2300 kg/hr, more preferably 1800 to 2100 kg/hr.

One key feature of the process according to the present invention is that temperature T2 is measured in predefined time intervals during steps (B), (C) and (D), and the at least one moiety for providing air (60) to the at least one secondary chamber is adjusted depending on a comparison of T2 with a value SP2 calculated from T2 of the forgoing time interval, wherein the first value SP2 is predefined at the beginning of step (B). According to the present invention the calculation of SP2 based on T2 of the foregoing time interval and the comparison of SP2 and T2 of the actual time interval provide information how much the moieties for introducing air into the secondary chamber shall be opened or closed in order to have the exact amount of air in the secondary chamber to obtain a complete combustion of the burnable gas that has not been burned in the primary chamber.

According to a preferred embodiment of the process according to the present invention, SP2 is calculated according to the following method:

The first value of SP2 is set by the operator. After certain a certain time interval, for example 20 minutes, temperature T2 is measured and the central processing unit calculates if the difference of SP2 and T2 (SP2 - T2) has increased or decreased during the time interval. For example, if SP2 - T2 has increased more than 2°C, preferably more 4 °C, SP2 is recalculated and the new SP2 is the old SP2 + 5 to 14 °C, for example + 9°C. Further, if SP2 - T2 has decreased more than 1 to 5 °C, for example 3 °C, SP2 is recalculated and the new SP2 is the old SP2 - 10 to 25 °C, for example - 17°C.

The present invention also relates to the process according to the present invention, wherein SP2 is 950 to 1370 °C, preferably 1050 to 1360 °C, more preferably 1100 to 1380 °C.

According to the present invention, a temperature T2 is measured and this temperature T2 used to calculate a setting point SP2. The first setting point SP2 at the beginning of step (C) is predefined by the operator of the process and may be 1100 to 1370 °C, preferably 1200 to 1360 °C. With T2 acquired after the first time interval and the first SP2 a new SP2 is calculated according to the above mentioned method. After a certain time interval, preferably 20 minutes, temperature T2 is measured again and is then used in order to calculate a new SP2 and so on. In each time interval, the comparison between T2 and the corresponding SP2 provides information if and how much the moiety for introducing air into the second chamber shall be opened or closed, if the new SP2 has increased in the calculation, the valve will open by a certain percentage, which is calculated by using the mathematical formula of the proportional-integral- derivative controller (PID), which is known to the skilled artisan. If the new SP2 has decreased in the calculation, the valve will close by a certain percentage, which is calculated by using the mathematical formula of the proportional-integral-derivative controller (PID). Therewith, which each comparison in each time interval the at least one moiety to introduce air (60) into the at least one secondary chamber is adjusted to have the exact amount of air in the secondary chamber, preferably to guarantee a complete combustion of burnable gas.

Generally, the time intervals for acquiring T2 and calculating a new SP2 can be selected by a person having ordinary skill in the art to obtain a suitable process. According to preferred embodiment, the time intervals in the process according to the present invention are 5 to 30 min, preferably 10 to 25 min, more preferably 15 to 22 min, for example 20 minutes. Further preferred, the time interval is kept constant during the whole process.

According to a further preferred embodiment, the present invention relates to the process according to the present invention, wherein the at least one moiety for providing air (60) to the at least one secondary chamber is closed completely, if the comparison of T2 and SP2 has the result that T2 has dropped by at least 2 °C per hour, preferably by at least 4 °C per hour, during the last time interval.

According to a preferred embodiment of the present invention, at the beginning of step (C) of the process according to the present invention, the cooking time is checked. Preferably, if the cooking time is lower than a certain value that depends on the kind and amount of coal and on the kind of coke oven, for example lower than 40 hours, preferably lower than 30 hours, more preferably lower than 24 hours, then temperature T2 will be checked for the first time. If T2 is higher than a certain temperature which depends on the coke oven and which is predefined in order to avoid damages to the oven, in particular to the bricks, the central processing unit preferably starts a cooling step (E) which will be explained in the following. For example, the temperature T2 at which the central processing unit starts the cooling step (E) is higher than 1350 °C, preferably higher than 1360 °C, particularly preferably higher than 1380 °C, for example 1385 °C.

Therefore, the present invention preferably relates to the process according to the present invention, wherein at least one cooling step (E), comprising

(E) Closing the at least one moiety for providing air (60) to the at least one secondary chamber completely, is conducted, if T2 is higher than 1350 °C, preferably higher than 1360 °C, particularly preferably higher than 1380 °C, for example 1385 °C, and if the cooking time is lower than 40 hours, preferably lower than 30 hours, more preferably lower than 24 hours.

Optional step (E) of the process according to the present invention can be conducted before, during or after step (C) of the process according to the present invention.

In case that T2 is lower than 1380 °C, preferably lower than 1375 °C, more preferably lower than 1370 °C, in particular lower than 1360 °C, the at least one moiety for introducing air into the secondary chamber will be opened completely, i.e. to 100%.

According to a further preferred embodiment, in case that the cooking time is higher than 24 hours, preferably higher than 30 hours, more preferably higher than 40 hours, temperature T2 will be checked. If, in this case, temperature T2 is higher than 1350 °C, preferably higher than 1360 °C, more preferably higher than 1370 °C, for example 1380 °C, a cooling step (E) will be started.

The present invention therefore preferably relates to the process according to the present invention comprising

(E) Closing the at least one moiety for providing air (60) to the at least one secondary chamber completely, is conducted, if cooking time is higher than 24 hours, preferably higher than 30 hours, more preferably higher than 40 hours, and temperature T2 is higher than 1360 °C, preferably higher than 1370 °C, more preferably higher than 1380 °C, for example 1385 °C.

If, at a cooking time of higher than 24 hours, preferably higher than 30 hours, more preferably higher than 40 hours, temperature T2 is lower than 1380 °C, preferably lower than 1370 °C, more preferably lower than 1360 °C, particularly preferably lower than 1350 °C, the central processing unit will start the mathematical calculation to obtain SP2 and adjust the position of the at least one moiety to introduce air (60) into the secondary chamber based on temperature T2 and SP2 of the last time interval. According to a further preferred embodiment, the calculation of SP2 and the comparison of SP2 and T2 provide information, If temperature T2 decreases more than 2 °C/hr, preferably more than 4 °C/hr in step (C) of the process according to the present invention. If temperature T2 decreases more than 2 °C/hr, preferably more than 4 °C/hr in step (C) of the process according to the present invention, this preferably means that no more burnable gas is present in the secondary chamber and the at least one moiety for introducing air (60) into the secondary chamber shall be closed completely. If temperature T2 does not decrease more than 2 °C/hr, preferably more than 4 °C/hr in step (C) of the process according to the present invention, this means that burnable gas is still present in the secondary chamber and the at least one moiety for introducing air (60) into the secondary chamber has to be opened to the value as calculated by the method as outlined above.

According to a further preferred embodiment of step (C) of the process according to the present invention, temperature T2 is acquired while the at least one moiety for introducing air (60) into the secondary chamber is closed. If, temperature T2 increases by more than 1 °C/10min, preferably by more 2 °C/10min while the at least one moiety for introducing air (60) into the secondary chamber is closed, then the central processing unit gives a signal to the at least one moiety for introducing air (60) into the at least one secondary chamber to open it again, more preferably up to a grade of opening as calculated based on T2 and SP2 as outlined above.

According to a further preferred embodiment, the present invention relates to the process according to the present invention, wherein the calculations and comparisons in respect of Tl, T2, SP1 and SP2 during steps (B), (C) and (D) are done by at least one central processing unit.

According to a further preferred embodiment, the present invention relates to the process according to the present invention, wherein Tl and T2 are measured by thermocouples present in the at least one primary chamber (10) or in the at least one secondary chamber (20), respectively.

Step (D):

Step (D) of the process according to the present invention comprises removing the off-gas obtained from steps (B) and (C) through the at least one collector (40). According to a preferred embodiment of the present invention, 100% by weight of the burnable gas are combusted in the at least one primary chamber and in the at least one secondary chamber. Therefore, the off-gas that is removed in step (D) of the process according to the present invention preferably comprise gases that are obtained from the combustion of the gas released from coal, preferably selected from the group selected from carbon dioxide, carbon monoxide, nitrogen oxides, water, and mixtures thereof and air.

The collector (40) which is used according to step (D) of the process according to the present invention is generally known to the skilled artisan.

According to a further preferred embodiment, the present invention relates to the process according to the present invention, wherein the at least one moiety for providing air (50) to the at least primary chamber and/or the at least one moiety for providing air (60) to the at least secondary chamber are independently of each other selected from the group consisting of a valve, a damper, gates or a combination thereof.

Generally, the at least one moiety for introducing air (50) into the primary chamber and/or the at least one moiety for introducing air (60) into the secondary chamber, may be opened or closed at any speed which a person having ordinary skill in art knows to be suitable. According to a preferred embodiment of the process according to the present invention the at least one moiety for introducing air (50) into the primary chamber and/or the at least one moiety for introducing air (60) into the secondary chamber, are opened or closed by 1 to 20% per minute, preferably 1 to 10% per minute.

The present invention further relates to a coke oven (1), comprising at least one primary chamber (10), at least one secondary chamber (20) located beneath the primary chamber, at least one connection (30) between the at least one primary chamber (10) and the at least one secondary chamber (20), at least one collector (40) which is connected to the at least one secondary chamber (20), at least one moiety for providing air (50) to the at least one primary chamber, at least one moiety for providing air (60) to the at least one secondary chamber and a central processing unit (70), wherein at least one thermocouple (80) is present and the at least one primary chamber (10) and at least one thermocouple (90) is present at the at least one secondary chamber (20), wherein the central processing unit (70) is enabled to compare a value SP1 and a temperature Tl that is measured in predefined time intervals and to adjust the at least one moiety for providing air (50) to the at least one primary chamber and compare a value SP2 and a temperature T2 that is measured in predefined time intervals and to adjust the at least one moiety for providing air (60) to the at least one secondary chamber.

The single features of the coke oven according to the present invention and preferred embodiments have been already been explained in respect of the process according to the present invention. This disclosure shall be applied to the coke oven of the present invention correspondingly.

The present invention further relates to the use of a coke oven according to the present invention to prepare coke from coal. The single features of the coke oven according to the present invention and preferred embodiments have been already been explained in respect of the process according to the present invention. This disclosure shall be applied to the use of the coke oven of the present invention correspondingly.

According to a preferred embodiment of the use according to the present invention, the preparation of coke from coal is conducted in the process according to the present invention.

The present invention therefore also relates to the use according to the present invention, wherein the preparation of coke from coal is conducted in a process according to the present invention.

Examples:

Example 1

In the following, an exemplified process according to the present invention is explained in detail.

The first predefined setpoint SP1 of an oven is 1350 °C. The cooking time is 52 hours and the top temperature Tl from the thermocouple is 1280 °C. The position of the top valve in this case is calculated according to the following equation:

Position of top valve in [%] = 1350 - 1280 = 70.

The top valve of the primary chamber will therefore be opened to a value 70%. Assuming that the top temperature Tl of this oven increases during eight hours to 1340 °C, then the new position of the top valve will be:

Position of top valve in [%] = 1350 - 1340 = 10.

The top valve of the primary chamber will therefore be opened to a value of 10%, i.e. the opening will be reduced from 70% to 10%.

The PID combustion will decrease the opening of the top valve and therefore decrease the flame size on the primary chamber with the main objective of reducing burn loss.

The central processing unit after each 20 minutes compares if (SP2 - T2) has increased or decrease by a certain °C, if SP2 - T2 has increased more than 4 °C, SP2 is recalculated and the new SP2 is the old SP2 + 9 °C, if not, if SP2 - T2 has decreased more than 3 °C, SP2 is recalculated and the new SP2 is the old SP2 - 17 °C. If the new SP2 has increased in the calculation, the valve will open by a certain percentage, which is calculated by using the mathematical formula of the proportional-integral-derivative controller (PID), if the new SP2 has decreased in the calculation, the valve will close by a certain percentage, which is calculated by using the mathematical formula of the proportional-integral-derivative controller (PID).

Example 2

Figure 2 shows the average temperature and valve position of 18 ovens at the same block. The temperature and valve positions are average in view of all 18 ovens being connected.

The cycle can be divided by 3 stages.

During the first 24 hours, stage 1, the primary chamber valve and the secondary chamber valve are 100% opened to burn the high amount of gas released from the coal cake.

During stage 2 it is possible to see the secondary chamber valve adjusting the opening because the gas released from the coal cake is not maximum. The secondary chamber valve keeps 100% open during this stage.

Stage 3 starts when the primary chamber valve starts to adjust the opening percentage to decrease the primary flame, with the objective of decreasing the burn loss and the gas not burned on the primary chamber goes to the secondary chamber. The secondary chamber valve will adjust the opening to completely burn the gas inside the secondary chamber and not send any gas to the collectors.

Even in the end of the cycle, after 63 hours when the primary chamber valve is closed the secondary chamber valve is open to burn the remaining gas inside the oven.

Example 3

While analyzing a single oven of the 18 ovens of example 2 with the process according to the present invention, it is possible to divide the cooking process in three stages.

The first stage of Figure 3, differently from the Figure 2, last for almost 42 hours, during this period the primary chamber valve and the secondary chamber valve keep mostly 100% open to burn the gas inside the oven.

In stage two the secondary chamber valve decreases the opening during 3 hours and then opens again.

Stage three last for 15 hours and has the primary chamber valve beginning the closing process and the secondary chamber valve adjusting to burn the gas not burned on in the primary chamber.

At the end of the process, the primary chamber valve and the secondary chamber valve close at the same time, meaning that there is no more gas to be burned.

Example 4

Figure 4 shows the oven which is described here has a stage 1 of 42 hours, where the primary and secondary valves are mostly 100% open. In stage 2 the primary chamber valve is closing due to the temperature increase in the primary chamber.

In stage 3 the primary chamber top valve is opened again due to a decrease of temperature in the primary chamber and then start the closing process as the top temperature starts to rise again.

In stage 4, both the secondary chamber valve is closed and after 60 hours the primary chamber valve is closed completely (100%). Example 5

Figure 5 shows an oven that has the stage 1 of 37 hours, where the three valves are mostly 100% open.

Stage 2 has the top valve closing due to the increase of temperature in the primary chamber. The sole flue valve of one side closed completely at 46 hours. The oven sole flue valve open and then start to close, after a small time it open again due to gas not burned completely on the Top.

Stage 3 has one sole flue valve and the Top valves closed, but the other sole flue valve is open to burn the remaining gas and not let it go to the collector.

Brief Description of Drawings

Below, the present invention is explained in more detail using figures. In particular, the following is shown:

Figure 1 shows a coke oven (1) which is preferably used to conduct the process according to the present invention. The references used in figure 1 have the following meanings:

1 Coal cake

2 Primary chamber or Top (10)

3 Air introduced into the primary chamber from environment

4 Primary chamber valve (50)

5 Downcomer (30)

6 Secondary chamber or Sole flue (20)

7 Air introduced into the secondary chamber from environment

8 Secondary chamber valve (60)

9 Collector (40)

10 Thermocouple in the primary chamber (80)

11 Thermocouple in the secondary chamber (90)

12 Central processing unit (70)

13 Signal to primary chamber valve to adjust grade of opening from 0 to 100% 14 Signal to secondary chamber valve to adjust grade of opening from 0 to 100%

Figure 2 shows the average temperature and valve position of 18 ovens at the same block. The temperature and valve positions are average in view of all 18 ovens being connected.

Figure 3 shows the temperatures and valve positions of an exemplary oven I . Figure 4 shows the temperatures and valve positions of an exemplary oven 2. Figure 5 shows the temperatures and valve positions of an exemplary oven 3. Industrial Applicability

The process according to the present invention is useful in the commercial production of coke from coal, wherein the above mentioned technical advantages are obtained. The coal that is produced accordingly can be used, for example, in the production of steel.